Windows that are displayed on a monitor for operating systems and graphical user interfaces are approximately rectangular boxes. Each window may be associated with an application, a dialog, a message box and the like. In some operating systems, each window is assigned a depth. Thus usually a single window is active and is a foreground window and all other windows are layered behind the foreground window.
Some windows can appear abruptly and interrupt a current foreground window. For example, a pop-up window can automatically appear as the foreground window deactivating the current window and sending the current window into the background behind the pop-up window. In certain applications, such automatic pop-up windows can be a nuisance and interrupt the applications.